1. Field of the Invention
The present invention relates to antialgal compositions, methods of controlling algae, and coating compositions comprising the antialgal compositions.
2. Description of the Prior Art
The presence of algae in various aqueous systems such as latices, paints, coatings, cooling water systems, decorative ponds and the like, can cause deterioration or disfigurement of these systems. For example, painted surfaces may be disfigured by the unsightly buildup of algae, thus detracting from the overall aesthetics of the painted article; cooling towers may lose efficiency due to the buildup of algae on surfaces, thus reducing the heat transfer capabilities of the tower. It is conventional to practice methods which inhibit the algal deterioration of such systems by incorporating a variety of additives or combination of additives that are characterized by having antialgal activity.
A wide variety of materials have been used to control algae in different environments, some of which are: chlorine/bromine compounds, glutaraldehyde, isothiazolones, organotin formulations, copper salts, quaternary ammonium compounds (S. D. Strauss and P. R. Puckorius in J. Power, S1, June 1984), and triazines. Each has deficiencies related to toxicity, pH and temperature sensitivity, limited effectiveness, chemical stability, and/or compatibility.
Different diphenylethers ("DPEs") have been found to have widely different antimicrobial properties. See, for example, halogenated hydroxy (acyloxy) DPEs (U.S. Pat. Nos. 3,772,445; 3,908,019), and nitro/trifluoromethyl DPEs (U.S. Pat. No. 4,112,002).
U.S. Pat. No. 3,787,217 and Japanese Kokai Patent Application 48-48624 to Nitta et al are directed towards the use of halogenated and alkyl substituted DPEs as paint antifouling agents and disclose the use of these materials to control growth of clams, barnacles, and shellfish larvae at 0.5-1.0 dosage levels.
Great Britain Paten 1,592,011 to Ciba-Geigy discloses the use of DPEs containing amino (or substituted amino) or hydroxy (or ester derivatives of organic/inorganic acids) substituents as algicides, particularly dichloro- and trichloro-substituted DPEs.
Lysozyme is an enzyme found in egg whites and acts as a mild antiseptic towards certain bacteria (Dictionary of Microbiology, p. 233, 1980, John Wiley & Sons). Lysozyme is composed of 129 aminoacid units and has a molecular weight of 14,500. Although lysozyme is known to have certain bactericidal properties, e.g., cheese making, its use as an antialgal agent has not been disclosed.
Based on the aforementioned performance deficiencies of conventional antialgal compounds there is a need for more effective antialgal agents that can be used at lower dosage rates, thus being more cost effective for the end user, reducing the pollution load on the affected environmental systems, and reducing the side effects to nearby non-target organisms, such as fish, useful crops, etc.